Electric double-layer capacitor

ABSTRACT

An electric double layered capacitor is provided, which can ensure a cooling capability by radiating heat to an outside air. The electric double layered capacitor comprises a capacitor cell  1  including a bag-shaped soft case in which a plurality of positive electrodes and negative electrodes, and a separator are received and laminated together with an electrolytic solution, a belt-shaped radiating fin  5   a  which extends from a rim of the soft case, a heat transfer frame  15  to sandwich the radiating fin  5   a , and a metal hard case  21  for thermal radiation in which a plurality of the capacitor cells  1  are received/laminated through the heat transfer frames  15.

FIELD OF THE INVENTION

The present invention relates to an improvement of an electric doublelayered capacitor used as an electric storage device.

BACKGROUND OF THE INVENTION

Recently, an electric double layered capacitor receives attention as anelectric storage device used for, for instance, a hybrid car, a windpower facility or the like, which is rechargeable quickly, as well ashas a long charge-discharge cycle length.

The conventional type of the electric double layered capacitor celldisclosed in Japanese Unexamined Patent Publication No. 3-203311Aincludes a bag-shaped soft case in which a plurality of positiveelectrodes and negative electrodes, and a separator are receivedtogether with an electrolytic solution to be laminated.

When this type of the electric double layered capacitor is mounted on avehicle or the like, it is required that a plurality of the electricdouble layered capacitors are received in parallel in a hard case toform a capacitor module, which is connected to a substrate of a controlcircuit for unitizing.

However, the capacitor module needs a cooling system to circulatecooling air around the capacitor module by, for instance, an electricfan to ensure thermal radiation of the electric double layered capacitorreceived in the hard case, which results in increasing in complexity andgrowing in size.

An object of the present invention is to solve the above problems.

It is an object of the present invention to ensure a better coolingcapability of a capacitor unit including a control substrate or thelike.

SUMMARY OF THE INVENTION

An electric double layered capacitor according to the present inventioncomprises a capacitor cell including a bag-shaped soft case in which aplurality of positive electrodes and negative electrodes, and aseparator are received together with an electrolytic solution to belaminated, a hard case for thermal radiation in which a plurality of thecapacitor cells are received and laminated to be closely contacted witheach other, and a thermal conductor interposed between the hard case andthe capacitor cells.

Heat generated in the capacitor cells in accordance with charge anddischarge of the capacitor cells is transmitted from the soft case tothe hard case for thermal radiation by the thermal conductor and thentransmitted from the hard case to an outside air to release the heat.

Further, an electric double layered capacitor according to the presentinvention comprises a plurality of capacitor cells in each of whichincludes in a bag-shaped soft case a plurality of positive electrodesand negative electrodes, and a separator are received together with anelectrolytic solution to be laminated, a capacitor module to receive andlaminate a plurality of the capacitor cells in a hard case for thermalradiation, a control box housing a control substrate to charge anddischarge the capacitor cells, and a capacitor unit formed of connectingthe control box to the capacitor module, wherein the hard case isexposed to an outside of the control box.

Since in the capacitor unit the control box is provided with thecapacitor module and the hard case of the capacitor module is placed tobe exposed to an outside of the control box, each capacitor module canbe sufficiently cooled by exposing an exterior of the hard case to theoutside air. Accordingly even when a plurality of the capacitor modulesare connected to one control box, it is possible to control a rise intemperature at the capacitor module, to ensure an output performance anda durability thereof without any use of specific cooling system.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. 1 is an exploded perspective view showing a capacitor module.

FIGS. 2A and 2B are a top view and a side view of the capacitor module.

FIG. 3 is a perspective view showing a capacitor cell.

FIG. 4 is a perspective view showing an electric heat frame.

FIG. 5 is a cross sectional view showing the capacitor module.

FIG. 6 is a cross sectional view showing a capacitor module according toanother embodiment.

FIG. 7 is a construction view showing a capacitor unit.

FIG. 8 is a perspective view showing the capacitor cell.

FIG. 9 is a cross sectional view showing the capacitor cell and a busbar.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention are described below with referenceto the accompanying drawings.

As shown in FIG. 1, FIG. 2A, and FIG. 2B, a plurality of electric doublelayered capacitor cells 1 are received and laminated in a hard case 21for thermal radiation so that they are closely contacted with each othertherein, which forms one capacitor module 20.

As shown in FIG. 3, each capacitor cell 1 includes a bag-shaped softcase 5 in which a positive electrode, a negative electrode and aseparator (not shown) are received together with an electrolyticsolution to be laminated.

The soft case 5 is formed by two elastic and laminated sheets 6 and 7jointed in a bag shape. In the soft case 5, the flanges 6 a and 7 a ofthe sheets 6 and 7 are welded to form a belt-formed radiating fin 5 asurrounding the edge of the soft case 5. The radiating fin 5 a is formedwider than a weld part of the flanges 6 a and 7 a to serve as releasingheat generated in a capacitor cell 1.

Terminal strips 9 and 10 of the electrodes to connect to the positiveelectrodes and the negative electrodes project from the upper side ofthe soft case 5.

As shown in FIG. 4, a heat transfer frame 15 sandwiches the radiatingfin 5 a surrounded by the soft case 5 from an outside of the radiatingfin 5 a excluding a side of the terminal strips 9 and 10. The heattransfer frame 15 is made of a high thermal conductivity material, forinstance, a combined material which is formed of mixing metal powdersuch as aluminum into an elastic resin such as silicon.

The heat transfer frame 15 includes a slit 15 a to sandwich theradiating fin 5 a, a pair of flanges 15 b disposed on both sides of theslit 15 a to join an end of the soft case 5, a pair of thick sandwichingmembers 15 c to press the slit 15 a from both sides, and a supportmember 15 d contacting the hard case 21 for thermal radiation to besupported, all of which are integrally produced by a resinmold-processing. Further, the heat transfer frame may be, not limited tothe above, formed by jointing a plurality of members.

As shown in FIG. 5, the capacitor cells 1 are mounted to the heattransfer frames 15, received and laminated in the hard case 21 forthermal radiation so that they are closely contacted in a line with eachother therein. In the hard case 21 for thermal radiation, the heattransfer frames 15 mounted to the capacitor cells 1 are compressed bythe neighboring heat transfer frames 15 each other to be deformedelastically, which results in that the flanges 15 b of each heattransfer frame 15 are closely contacted to the ends of the soft case 5with no clearance, the slit 15 a of the heat transfer frame 15 isclosely contacted to the radiating fin 5 a with no clearance, as well asa rim of a support member 15 d is closely contacted to the inner surfaceof the hard case 21 for thermal radiation.

Therefore, the heat transfer frame 15 has functions of transmitting heatgenerated at the capacitor cell 1 from the radiating fin 5 a to the hardcase 21 for thermal radiation, elastically supporting the capacitor cell1 to the hard case 21 for thermal radiation and electrically insulatingthe capacitor cell 1 to the hard case 21 for thermal radiation.

The cross sectional shape of the heat transfer frame 15 may be, notlimited to this shape, for example, formed in a substantially simplerectangle-shape having a slit opened in an inside of the heat transferframe 15.

Further, the heat transfer frame 15 is not limited to a frame thatsurrounds three sides of the radiating fin 5 a with a top side of theframe being opened, but formed like a square frame that surrounds foursides of the radiating fin 5 a. Further, the heat transfer frame 15 maybe divided into four members corresponding to each side of the radiatingfin 5 a.

As shown in FIG. 6, instead of the heat transfer frame 15 functioning asa thermal conductor, a caulking compound 19 such as silicon may befilled between the soft case 5 and the hard case 21 for thermalradiation. The radiating fin 5 a of the capacitor cell 1 is folded andwrapped with the caulking compound 19.

In this case, the caulking compound 19 has functions of conducting heatgenerated at the capacitor cell 1 from the radiating fin 5 a to the hardcase 21 for thermal radiation, elastically supporting the capacitor cell1 to the hard case 21 for thermal radiation and electrically insulatingthe capacitor cell 1 to the hard case 21 for thermal radiation.

The hard case 21 for thermal radiation is, for instance, made of metalwith a high thermal conductivity such as an aluminum material toactively release heat at each capacitor cell 1 to the open air.

As shown in FIG. 1 and FIG. 2, a plurality of the capacitor cells 1 arereceived in one hard case 21 for thermal radiation to form a capacitormodule 20.

A pressure system 30 is provided at the midsection of the capacitormodule 20 and presses each laminated capacitor cell 1 in the oppositedirection so that they are closely contacted with each other. Thisurging force increases a density of an active carbon layer including apositive electrode and a negative electrode of the capacitor cell 1,thereby to enhance charge and discharge efficiencies. The capacitorcells 1 are also closely received in the hard case 21 for thermalradiation so as to be held under compression to prevent the capacitorcells 1 from deviating due to vibrations or impulses.

The pressure system 30 is disposed at such a place that a plurality ofcapacitor cells 1 are equally divided into two in the laminateddirection, in which one group of a plurality of capacitor cells 1 arepressurized between one end of the hard case 21 for thermal radiationand the pressure system 30, while the other group of a plurality of thecapacitor cells 1 are pressurized between the other end of the hard case21 for thermal radiation and the pressure system 30. Like this, onepressure system 30 simultaneously pressurizes two capacitor cell groups,which results in that one pressure system 30 allows many capacitor cells1 to be pressurized, to reduce the number of the pressure systems 30disposed in the capacitor module 20.

Further, the position of the pressure system 30 is not limited to aplace where the capacitor cells are divided equally, but may be providedin a place where the capacitor cells are divided into groups of apredetermined ratio as needed.

The pressure system 30 includes a stopper board 31 secured on top of thehard case 21 for thermal radiation, a pair of push plates 32 and 33which are surrounded by the stopper board 31 and the hard case 21 forthermal radiation, as well as are slidable in the laminated direction, abelleville spring 34 disposed between these push plates 32 and 33, aswell as to urge them in the direction to separate these push plates eachother, a setting bolt 35 to adjust a spring load of the bellevillespring 34 and the like.

Therefore, the spring load of the belleville spring 34 can be freelyadjusted by the setting bolt 35 increasingly or decreasingly such thatextending the setting bolt 35 increases the spring load of thebelleville spring 34, which results in that the force of urging the pushplates 32 and 33 each other increases, while shortening the setting bolt35 decreases the force of urging the push plates. 32 and 33.

FIG. 7 is a construction view showing a capacitor unit 40.

The capacitor unit 40 is formed by a combination of the capacitor module20 and a control box 41 housing a control substrate 42 to controlstorage and discharge of electricity in the capacitor module 20.

In this embodiment, three capacitor modules 20 disposed in parallel arepaired with one control box 41 to form one capacitor unit 40 and twocapacitor units 40 are overlapped one above the other to form acapacitor device.

The control box 41 housing the control substrate 42 is equipped with abase board 43 having the strength needed as a structural member. Thecontrol substrate 42 is mounted on the base board 43 by an electricallyinsulated support member 45. A box shaped cover 44 is mounted on top ofthe base board 43 and covers the control substrate 42.

Each capacitor module 20 is joined to the base board 43 of the controlbox 41. Each capacitor module 20 is mounted to the base board 43 so thatthe terminal strips 9 and 10 of electrodes are received in the controlbox 41, as well as are positioned under the control substrate 42.

The hard case 21 for thermal radiation of each capacitor module 20 isexposed to an outside of the control box 41 so that the outer surface ofthe hard case 21 for thermal radiation opens directly to an outside air.

The three capacitor modules 20 disposed in parallel under one of thecontrol box 41 have an opening of which size corresponds to a size ofeach hard case 21 for thermal radiation, in which the hard case 21 isengaged to be secured and supported to the control box 41 by hangingfrom the control box 41.

Each hard case 21 for thermal radiation exposed to an outside of thecontrol box 41 is disposed in parallel at a predetermined interval eachother. When the capacitor unit 40 is mounted on a vehicle, each hardcase 21 for thermal radiation is disposed to extend in the front-reardirections of the vehicle and a traveling wind (an outside air) flowsbetween each of the hard cases 21 for thermal radiation to cool eachhard case 21 equally.

When the two capacitor units 40 disposed above and below each other aremounted on the vehicle, the capacitor units are fixedly supported by asupport frame disposed on the vehicle body side (not shown) at apredetermined interval in an upward and downward directions. In thiscase, the base board 43 area of the control box 41 is secured by thesupport frame. Further, there is provided an under guard 47 surroundingeach hard case 21 for thermal radiation of the lower-side capacitor unit40 for protection thereof.

Inside the control box 41 for each capacitor unit 40 each of theterminal strips 9 and 10 of the three capacitor modules 20 and thecontrol substrate 42 are electrically linked by a plurality of the busbars 51.

The bus bar 51 extending across over three capacitor modules 20 and madeof a conductive metal is disposed under the control substrate 42. Aplurality of bus bars 51 corresponding to the capacitor cells 1 each aredisposed in the laminated direction of the capacitor cells 1 at equalintervals.

In each capacitor module 20, many capacitor cells 1 are arranged so asto be laminated by sequentially connecting each of the neighboringcapacitor cells in series. With this, the capacitor cells 1 each areplaced alternately in direction, whereby the terminal strips are facedwith the different electrodes. Namely, as understood by referring toFIG. 8, a terminal strip 9 of a certain cell and the terminal strip 10of the neighboring cell are faced each other, wherein the faced terminalstrips are directly connected with each other or connected through thebus bar 51.

In this embodiment, each terminal strip 9, 9, 9 of the capacitor cellreceived in each of the three capacitor module 20 respectively isconnected to each bus bar 51, while other terminal strips 10, 10, 10 areconnected to the neighboring bus bar 51, and the three capacitor cells 1are electrically connected in parallel over each capacitor module 20.

Both ends of each bus bar 51 are supported by the insulated supportmember 45 and a midpoint of the bus bar 51 is supported by the controlsubstrate 42 through an electrically insulated support member. A bossmade of a conductive member is welded at a midpoint of the bus bar 51 toelectrically connect the control substrate 42 to the bus bar 51, and thecontrol substrate 42 is fastened to each boss by an electrical screw.The control substrate 42 is mechanically fastened to the bus bar 51 bythe bosses and the screws, as well as the bus bar 51 is electricallyconducted to the control circuit of the control substrate 42.

Herein, as shown in FIGS. 8 and 9, the terminal strips 9 and 10 of eachelectrode at the capacitor cells 1 may be curved.

Namely, the terminal strips 9 and 10 of each electrode at the capacitorcells 1 are curved in s-shape at cross section to the laminateddirection of the capacitor cells, and each terminal strip 9 and 10 ofthe neighboring capacitor cell is disposed in the laminated direction ofthe capacitor cell is joined, as well as is welded to each bus bar 51.

Therefore, in each capacitor module 20, a plurality of the capacitorcells 1 are electrically connected in series, as well as the threecapacitor modules 20 are also connected to each other in parallel.

Since the terminal strips 9 and 10 made of aluminum are curved toconnect to the bus bar 51, a displacement of the capacitor cell 1 in thelaminated direction of the capacitor cell 1 to the bus bar 51 is easilyabsorbed by an elastic deformation of each of the terminal strips 9 and10, thereby to prevent a rupture even when a joining section of eachterminal strip 9, 10 and the bus bar 51 is overloaded by a mechanicalvibration and a thermal deformation.

The control circuit mounted to the control substrate 42 may charge sothat a voltage of each capacitor cell 1 does not exceed a predeterminedvalue, as well as control an equalization of the voltage stored at eachcapacitor cell 1.

As constructed above, in the present invention, heat generated in thecapacitor cell 1 caused by charge and discharge of the capacitor cell 1is transmitted from the radiating fin 5 a of the soft case 5 to the hardcase 21 for thermal radiation through the heat transfer frame 15 andthen transmitted from the hard case 21 for thermal radiation to theoutside air.

Further, the hard case 21 for thermal radiation is projected from thecontrol box 41 downwardly and exposed to the outside air, which resultsin that each capacitor cell 1 can be sufficiently cooled.

Accordingly, a temperature increase can be controlled without coolingthe periphery of the capacitor module needed by the conventional type ofthe specific cooling system, and therefore the cooling system becomesunnecessary, which results in facilitating a simplification in theconstruction of the capacitor unit.

Three capacitor modules 20 are disposed in a row per one control box 41,which enables both to ensure a cooling capability of each capacitormodule 20 as well as to reduce the size of the capacitor unit 40.

It is to be noted that four or more capacitor modules 20 may be disposedin a row per one control box 41.

While the present invention is not limited by any of the details ofdescription as described the above, it is understood that variousimprovements and modifications may be made within the scope of thepresent inventive concepts described in the following claims.

INDUSTRIAL FIELD OF APPLICATION

As described the above, the electric double layered capacitor accordingto the present invention may be applied for various types of capacitorsincluding a capacitor used for a hybrid car or a wind power facility.

1. An electric double layered capacitor comprising: a capacitor cellincluding a bag-shaped soft case in which a plurality of positiveelectrodes and negative electrodes, and a separator are received andlaminated together with an electrolytic solution; a hard case forthermal radiation in which a plurality of the capacitor cells arereceived and laminated to be closely contacted with each other; and athermal conductor interposed between the hard case and the capacitorcells.
 2. The electric double layered capacitor as defined in claim 1,wherein: a belt-shaped radiating fin is disposed in a rim of the softcase so as to be extended therefrom; and a heat transfer frame is placedin a periphery of the soft case as the thermal conductor, as well assandwiches the radiating fin.
 3. The electric double layered capacitoras defined in claim 2, wherein: the heat transfer frame is made of anelastic resin and thereby the neighboring heat transfer frames arecompressed with each other to be closely contacted.
 4. The electricdouble layered capacitor as defined in claim 3, wherein: the heattransfer frame is made by mixing with the elastic resin metal powderwith a high thermal conductivity such as aluminum.
 5. The electricdouble layered capacitor as defined in claim 1, wherein: a belt-shapedradiating fin is disposed in a rim of the soft case so as to be extendedtherefrom; and a caulking compound is filled between the soft case andthe radiating fin to wrap the radiating fin as the thermal conductor. 6.An electric double layered capacitor comprising: a bag-shaped soft casein which a plurality of positive electrodes and negative electrodes, anda separator are received and laminated together with an electrolyticsolution; a capacitor cell provided with the soft case; a capacitormodule to receive and laminate a plurality of the capacitor cells in ahard case for thermal radiation; a control box receiving a controlsubstrate to control charge and discharge of the capacitor cells; and acapacitor unit formed of connecting the control box to the capacitormodule, wherein: the hard case is exposed to an outside of the controlbox.
 7. The electric double layered capacitor as defined in claim 6,wherein: a plurality of the capacitor modules are arranged in parallelto the one control box.
 8. The electric double layered capacitor asdefined in claim 7, further comprising: a bus bar disposed in thecontrol box to extend over the respective capacitor modules, wherein:the capacitor cells received in each capacitor module are connected inparallel by the bus bar; and the bus bar is connected to the controlsubstrate.
 9. The electric double layered capacitor as defined in claim8, wherein: each of the capacitor cells arranged so as to be laminatedin the capacitor module is connected in series each other by the busbar.
 10. The electric double layered capacitor as defined in claim 8,wherein: the capacitor cells include each terminal strip to connect thepositive electrodes and negative electrodes to the bus bar; and the eachterminal strip is curved in the laminated direction of the capacitorcells to absorb a displacement of the capacitor cells to the bus bar.